1. Field of the Invention
This invention relates to a system and method for storing and retrieving magnetic tape cassettes of the kind ordinarily used for video, analog and digital sound, and for back-up of computer data. More particularly it relates to a tape transport platform for recording data on and reading data from magnetic tape cartridges or cassettes. The invention is described as incorporated in a computer data back-up system.
2. Description of Related Art
Magnetic tape cassettes are in wide use for recording and playing back both analog and digital signals. One particular application is for providing a back-up storage system for computer data. Such tape cassettes require little room and are capable of storing large amounts of data. In many instances, the cassettes are placed in and removed from the tape drive system manually. Various kinds of devices have been proposed for storing and recovering the tape cassettes automatically.
U.S. Pat. No. 3,603,597 to Haake describes a system for storing a number of cassettes in a storage bin and successively loading the cassettes into and removing them from a play station. A storage bin holds a number of cassettes in a vertical stack. The cassettes are removed from the bottom position and restored to the top position of the bin. The cassettes move vertically by gravity while in the bin, so horizontal operation of the bin is not feasible. The cassette gripper consists of a u-shaped member that receives the cassette through an open end which prohibits loading the cassette from one of the lengthwise edges.
U.S. Pat. No. 3,658,193 to Gross describes a cassette storage system in which the cassettes are stacked in a hopper positioned above the tape player. The cassettes are successively placed in the tape player and then discharged from the player into a discharge hopper. The cassettes are not returned to the original storage hopper.
U.S. Pat. No. 3,797,923 to Thavenaz shows a cassette handling mechanism in which image cassettes are moved into position for projection and then rewound automatically when returned to storage status.
U.S. Pat. No. 3,848,264 to Wilson shows a cassette storage chamber in which the casettes are positioned on edge in a horizontal row. A transducer for playing the tapes is mounted for horizontal movement along the row of cassettes. The cassettes are not moved individually from a storage position to a play position.
U.S. Pat. No. 3,883,895 to Kawsharasaki shows a cassette storage arrangement in which a first compartment contains cassettes to be positioned in the player while a second compartment receives the cassettes after playing and replaces a cassette from the second compartment as the bottom most cassette in a stack of cassettes in the first compartment. No arrangement for gripping and handling individual cassettes away from the storage chamber is shown.
U.S. Pat. No. 4,071,857 to Whitney et al. discloses a cassette handling system in which cassettes from a first storage magazine are fed into a player and from the player into a separate output magazine. The cassettes are conveyed by an endless conveyor. No system is shown for handling individual cassettes away from the storage compartment.
U.S. Pat. No. 4,860,133 to Baranski describes a large cassette library in which cassettes are loaded manually into one side of the storage assembly and removed automatically from the other side for playing. No mechanism for handling individual cassettes apart from the storage assembly is described.
Most of the previous cassette storage systems are large relative to the tape drive mechanism and are not generally applicable to the back up of computer data where it is desirable to position a cassette magazine within the computer cabinet or as a separate compact cassette storage and tape drive.